GOD_b <- as.Date("1920/2/14")
GOD_d <- as.Date("2020/2/14")
as.numeric(difftime(GOD_d, GOD_b, unit="days")) / 365

## [1] 100.0685

bDays <- seq(from=GOD_b, to=GOD_d, by="years")
Sat<- sum(weekdays(bDays) %in% c("星期六"))
Sun<- sum(weekdays(bDays) %in% c("星期日"))
Mon<- sum(weekdays(bDays) %in% c("星期一"))
Tue<- sum(weekdays(bDays) %in% c("星期二"))
Wed<- sum(weekdays(bDays) %in% c("星期三"))
Thu<- sum(weekdays(bDays) %in% c("星期四"))
Fri<- sum(weekdays(bDays) %in% c("星期五"))

library(lattice)
week <- c(Mon,Tue,Wed,Thu,Fri,Sat,Sun)
plot(week)
grid()