I have this data frame:
RANKING.Country.or.Area Year Average..last.5.years. GDP
1 Afghanistan 1970 629.0927
2 Afghanistan 1971 610.3037
3 Afghanistan 1972 496.1446
4 Afghanistan 1973 496.7760
5 Afghanistan 1974 mean(1970:1974) 510.7517
6 Afghanistan 1975 mean(1971:1975) 530.4223
7 Afghanistan 1976 mean(1972:1976) 548.2869
8 Afghanistan 1977 mean(1973:1977) 511.5458
9 Afghanistan 1978 mean(1974:1978) 542.5502
10 Afghanistan 1979 mean(1975:1979) 526.2770
11 Afghanistan 1980 mean(1976:1980) 509.6642
12 Afghanistan 1981 mean(1977:1981) 529.3375
The related time series is 1970:2014 and it contains about 9000 rows for 187 Countries.
I should find a way in r to calculate - in the column "Average..last.5.years." - the 'dynamic' mean of GDP over the last 5 years, considering any year and any Country variation (i.e. for 1975, the mean 1971:1975; for 1990, the mean 1986:1990 and so on).
