The next table shows the "anomalies" (good or bad luck) in every year. A positive anomaly means the driver was lucky in that year, getting a title that perhaps he could have not got. Negative means he was unfortunate because he didn't get the title but he could have got it.
Code:
12 11 10 09 08 07 06 05 04 03
VET +48 0 +66 -19
ALO -47 0 -27 0 0 -28 +25 +17
RAI -1 0 0 0 -5 +63 0 -17 0 -37
HAM 0 0 -16 0 +54 -30
BUT 0 0 -4 +31
MAS 0 0 0 0 -45 -5
Basically almost everyone has been lucky some times and unlucky other times, but not necessarily in the same amount.
The most notable instances of (good or bad) luck regarding titles are:
1) Vettel in 2010: He got the title against a close package of candidates. Bootstrap calculations shows had only a 34% probability of being WDC (the others shared the remaining probability).
2) Raikkonen in 2007: this is a well known case. Kimi was fortunate because the title race was extremely close between three drivers. Basically they played a virtual roulette.
3) Hamilton in 2008: Another well known case. Poor Massa.
4) Vettel in 2012: His (other) close title against Alonso.
5) Alonso in 2012! : The reverse side of the former event. This is the unluckiest case in the whole table.
6) Massa in 2008: Obvious, I suppose.