I would like to replace the parenthesis and the text between parenthesis in string variables. However I only want to replace those parenthesis with at least one number in it.

Example string: 

```
text <- c("Sekretär (dipl.) (G3)", "Zolldeklarant (3 Jahre)", "Grenzwächter (< 2 Jahre)")

```

I tried the following: 

```
str_extract_all(text, " *\\(.*?\\d+.*?\\) *")

```

It does extract the text in parenthesis, but in the first one, it matches also the first parenthesis without any number. 

The extraction should look like:

```
" (G3)"
" (3 Jahre)"  
" (< 2 Jahre)"

```