ddply summary issue

General
4 
library(dplyr)

df %>% 
    group_by(year, hy) %>% 
    summarise(A2TB = mean(A2TB),
              B1 = mean(B1),
              C1 = mean(C1),
              D1 = mean(D1, na.rm = TRUE),
              E1 = mean(E1),
              F1 = mean(F1),
              G1 = mean(G1),
              count = n())
#> # A tibble: 3 x 10
#> # Groups:   year [2]
#>    year    hy  A2TB    B1    C1    D1    E1    F1    G1    count
#>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <int>
#> 1  2017     1  75    82.5  86.2  61.4  88.8  86.2  53.8     8
#> 2  2018     1  91.3  92.6  95.7  91.3  93.9  95.7  73.5     23
#> 3  2018     2  63.2  90    91.6  81.8  92.1  92.6  54.7     19