Why do I see symbolic links to a directory in '/var/log/sa'?

Issue

• Why do I see symbolic links in /var/log/sa ?

See a sample:

[root@server01 sa]# ls -lt
total 16532
lrwxrwxrwx 1 root root     11 Jun 20 07:22 sa20 -> 201606/sa20
drwxr-xr-x 2 root root   4096 Jun 20 00:00 201606
lrwxrwxrwx 1 root root     11 Jun 19 23:59 sa19 -> 201606/sa19
lrwxrwxrwx 1 root root     12 Jun 19 23:53 sar19 -> 201606/sar19
lrwxrwxrwx 1 root root     11 Jun 18 23:59 sa18 -> 201606/sa18
-rw-r--r-- 1 root root 290026 Jun 17 23:53 sar17
-rw-r--r-- 1 root root 302868 Jun 17 23:50 sa17
-rw-r--r-- 1 root root 290026 Jun 16 23:53 sar16