Oracle SQL : Getting average for past 3 month and add additional column
<p>I have below table in Oracle and i need to create a view from this table to calculate of the average score for the past 3 months in additional column.</p>

<pre><code>Name      YearMonth     Score
Vince     201507         97
Vince     201508         95
Vince     201509         94
Vince     201510         91
Vince     201511         98
Vince     201512         95
Vince     201501         93     
</code></pre>

<p>Expected output:</p>

<pre><code>Name      YearMonth     Score   Average
Vince     201507         97      
Vince     201508         95        
Vince     201509         94      95.33 ((97+95+94)/3)
Vince     201510         91      93.33 ((95+94+91)/3)
Vince     201511         98      94.33 ((94+91+98)/3)
Vince     201512         95      94.67 ((91+98+95)/3)
Vince     201501         93      95.33 ((98+95+93)/3)
</code></pre>

<p>How can I do it using SQL? Thank you for the help</p>