Finding the peak density by plotting in R

Question

I'm learning to plot the density in R

This is what the sample looks like:

# A tibble: 10 x 2
   start_time1 ClusterNumber
         <dbl> <chr>        
 1        6.72 2            
 2        6.82 2            
 3        7.57 1            
 4        6.57 3            
 5        6.31 2            
 6        6.30 2            
 7        6.60 2            
 8       16.4  4            
 9       16.1  3            
10       16.0  1 

 data <- structure(list(start_time1 = c(6.72472222222222, 6.82194444444444,7.57361111111111, 6.56611111111111, 6.31111111111111, 6.29916666666667,6.59555555555556, 16.3666666666667, 16.1305555555556, 16.0111111111111), ClusterNumber = c("2", "2", "1", "3", "2", "2", "2", "4","3", "1")), row.names = c(NA, -10L), class = c("tbl_df", "tbl","data.frame")) 

So far, I have tried to plot the density separate with ClusterNumber;

ggplot(data, aes(x=start_time1)) + 
  geom_density(aes(group=ClusterNumber, colour=ClusterNumber, fill=ClusterNumber), alpha=0.1)+
  labs(title="Starting time distribution",x="Starting Time (Hrs)", y = "Density")

This is my result;

However, I want to find the high-density value. How can I find it? using abline? Can I extract the exact value of the graph? Thank you in advance.