年収のカテゴリーを連続変数へ(JGSS)
0 <- 1,
35 <- 2,
85 <- 3,
115 <- 4,
140 <- 5,
200 <- 6,
300 <- 7,
400 <- 8,
500 <- 9,
600 <- 10,
700 <- 11,
800 <- 12,
925 <- 13,
1100 <- 14,
1300 <- 15,
1500 <- 16,
1725 <- 17,
2075 <- 18,
2300 <- 19,
99 <- 20,
99 <- 21,
"無回答" = 99 <- 99,
otherwise = "copy"