I have a panel data in the form of data frame like this I have many countries and many observations for each one. My goal is to count the number of countries that appear in the data frame and how many times each country appears
An example of my data frame is below
> ff
cross_id date_id E.tertiary lv18_bank_c
1 Albania 1982 2.13747 0
2 Albania 1984 2.22216 0
3 Albania 1985 1.80637 0
4 Albania 1986 1.82942 0
5 Albania 1987 2.06611 0
6 Albania 1988 3.85074 0
7 Albania 1989 2.89562 0
8 Albania 1990 2.05454 0
9 Albania 1991 2.57309 0
10 Albania 1992 3.84439 0
11 Albania 1993 4.26285 0
12 Albania 1994 3.57016 1
13 Albania 1995 4.90303 0
14 Albania 1996 5.70181 0
15 Albania 1997 5.37198 0
16 Albania 1998 3.95752 0
17 Albania 1999 6.34027 0
18 Albania 2000 8.44206 0
19 Albania 2001 11.10053 0
20 Albania 2002 14.78250 0
21 Albania 2003 15.78137 0
22 Albania 2004 16.72831 0
23 Albania 2005 24.65881 0
24 Albania 2006 26.68887 0
25 Albania 2007 32.61487 0
26 Albania 2008 33.94730 0
27 Albania 2009 33.69017 0
28 Albania 2010 28.62207 0
29 Albania 2011 13.83260 0
30 Albania 2012 7.49656 0
31 Albania 2013 -4.29068 0
32 Algeria 1988 1.94325 0
33 Algeria 1989 1.60497 0
34 Algeria 1991 1.12511 0
35 Algeria 1994 2.73635 0
36 Algeria 1996 5.49956 0
37 Algeria 1997 5.95291 0
38 Algeria 2000 7.14822 0
39 Algeria 2002 7.94752 0
40 Algeria 2004 11.33143 0
41 Algeria 2005 10.74001 0
42 Algeria 2006 10.34123 0
43 Algeria 2007 10.86369 0
44 Algeria 2008 10.28966 0
45 Algeria 2010 6.87194 0
46 Algeria 2011 12.73942 0
47 Algeria 2012 16.43274 0
48 Algeria 2013 19.16414 0
49 Argentina 1981 15.69030 0
50 Argentina 1982 16.11802 0
51 Argentina 1986 2.62316 0
52 Argentina 1995 16.96348 1
53 Argentina 1999 18.52467 0
54 Argentina 2000 15.13495 0
55 Argentina 2001 12.99992 1
56 Argentina 2002 7.40008 0
57 Argentina 2003 5.30822 0
58 Argentina 2004 5.03020 0
59 Argentina 2005 7.74603 0
60 Argentina 2006 12.33073 0
61 Argentina 2007 10.48156 0
62 Argentina 2008 11.81227 0
63 Argentina 2009 12.93886 0
64 Argentina 2010 13.79554 0
65 Argentina 2011 13.98205 0
66 Argentina 2012 13.66112 0
67 Armenia 1987 7.74252 0
68 Armenia 1989 0.32560 0
69 Armenia 1990 -1.35376 0
70 Armenia 1991 -6.26625 0
71 Armenia 1992 -2.63647 0
72 Armenia 1993 8.23146 0
73 Armenia 1994 12.18477 1
74 Armenia 1995 16.42548 0
75 Armenia 1996 14.46316 0
76 Armenia 1997 19.20829 0
77 Armenia 1998 14.49865 0
78 Armenia 1999 4.30956 0
79 Armenia 2000 4.33436 0
80 Armenia 2001 7.56556 0
81 Armenia 2002 12.38564 0
82 Armenia 2003 12.34247 0
83 Armenia 2004 14.11571 0
84 Armenia 2005 15.10601 0
85 Armenia 2006 13.79101 0
86 Armenia 2007 3.04268 0
87 Armenia 2008 -0.19355 0
88 Armenia 2009 -1.40714 0
89 Armenia 2010 -4.81279 0
90 Armenia 2011 -1.90896 0
91 Armenia 2012 -1.08625 0
92 Armenia 2013 8.41245 0
93 Austria 1981 5.33637 0
94 Austria 1982 5.51511 0
95 Austria 1983 6.90563 0
96 Austria 1984 7.59978 0
97 Austria 1985 8.59364 0
98 Austria 1986 9.16943 0
99 Austria 1987 10.90617 0
100 Austria 1988 11.95211 0
101 Austria 1989 12.89434 0
102 Austria 1990 14.38936 0
103 Austria 1991 14.95411 0
104 Austria 1992 14.87273 0
105 Austria 1993 14.78557 0
106 Austria 2008 16.60811 1
107 Austria 2009 13.27180 0
108 Austria 2010 12.60677 0
109 Austria 2011 7.83117 0
110 Austria 2012 6.55769 0
111 Bangladesh 1981 1.73887 0
112 Bangladesh 1982 1.22771 0
113 Bangladesh 1983 -0.08311 0
114 Bangladesh 1984 -1.00364 0
115 Bangladesh 1985 -0.83548 0
116 Bangladesh 2000 0.81326 0
117 Bangladesh 2001 1.72986 0
118 Bangladesh 2002 1.28143 0
119 Bangladesh 2003 2.53967 0
120 Bangladesh 2004 4.46713 0
121 Bangladesh 2006 7.24486 0
122 Bangladesh 2007 6.43980 0
123 Bangladesh 2009 4.98099 0
124 Bangladesh 2012 4.45990 0
125 Bangladesh 2013 6.76407 0
126 Belarus 1981 7.19799 0
127 Belarus 1982 7.01108 0
128 Belarus 1983 7.67367 0
129 Belarus 1984 7.01828 0
130 Belarus 1985 6.93979 0
131 Belarus 1986 3.79298 0
132 Belarus 1987 -1.31170 0
133 Belarus 1988 -3.02827 0
134 Belarus 1989 -5.95809 0
135 Belarus 1990 -7.48738 0
136 Belarus 1991 -4.60565 0
137 Belarus 1992 -2.63166 0
138 Belarus 1993 5.38768 0
139 Belarus 1994 8.98458 0
I need to count how many countries appear in this data frame and also the number of how many times they appear.
For example like this:
Number of countries - 52
Albania - 30
Algeria - 17
etc
