The following script gives this kind of output (for only 3 days of logs...) : 

# ./sshhack-iploc /var/log/auth.log*
-----------------------------
-- SSH failed distinct attempts by country
Hong Kong -> 42
China -> 38
France -> 10
United States -> 6
Germany -> 2
Venezuela -> 1
United Kingdom -> 1
India -> 1
Republic of Korea -> 1
Brazil -> 1
Netherlands -> 1
-----------------------------
-- SSH top 10 of tested users
User 'root' -> 78318
User 'admin' -> 158
User 'oracle' -> 21
User 'postgres' -> 18
User 'ts' -> 14
User 'vnc' -> 13
User 'test' -> 12
User 'bin' -> 12
User 'git' -> 11
User 'teamspeak3' -> 10
-----------------------------
-- General Information
Processed time range : 92 hours (~3 days)
Total number of auth failures 78757 (~856 by hour)
Distinct tested logins 116