| 2017 | 2018 | 2019 |
Cost of Sales | $4160 | $5623 | $7064 |
% of Rev | 52% | 50% | 43% |
Research Development | $1201 | $1505 | $2493 |
% of Rev | 15% | 13% | 15% |
SG&A | $6141 | $6749 | $7479 |
% of Rev | 77% | 60% | 45% |