Converting data in time series

General
1

Hi everybody!
I have problem of converting my excel data in time series with RStudio 4.3.1
When I import data from excel, RStudio have the option of categorizing the variable. If I convert in Date, the program change the format from yearly data to daily data.
If I use as.Date function for the file "GDP1" and time variable into the data "Time" by the script : GDP1$Time<- as.Date(GDP1$Time)
the program give the message
Error in charToDate(x) :
character string is not in a standard unambiguous format
How can I deal with it?

2

Look at

?as.Date

and give a format or tryformat argument that makes clear how the dates are written.