Pie Chart - Combine Values

Hello all,

I tried to search for what I'm trying to do but I didn't know how to word it exactly. I would like to create a pie chart but combine values. In other words, my data looks something like this:

1. Piano: 10
2. Banjo: 1
3. Flute: 1
4. Guitar: 3
5. Sitar: 2

If I make a pie chart right now, it will show me:

1. Piano: 59%
2. Banjo: 6%
3. Flute: 6%
4. Guitar: 17%
5. Sitar: 12%

As expected. However, I'd like to somehow combine the values, so the output looks more like this:

1. Piano: 59%
2. Other: 41%

I considered making a calculated column somehow but I didn't know what to put in it: If([Instrument]="Piano",........?)

Could someone please help me out?