Table:
|  | Year Ended December 31, |  | Change |  |
| --- | --- | --- | --- | --- |
|  | 2019 | 2018 | $ | % |
|  |  | (dollars in thousands) |  |  |
| Sales and marketing | $ 87,731 | $ 69,608 | $ 18,123 | 26.0% |
| % of revenue | 44% | 47% |  |  |
Paragraphs:
Sales and Marketing Expense
Sales and marketing expense increased by $18.1 million in 2019 compared to 2018. The increase was primarily due to a $15.5 million increase in employee-related costs, which includes stock-based compensation, associated with our increased headcount from 286 employees as of December 31, 2018 to 345 employees as of December 31, 2019. The remaining increase was principally the result of a $1.2 million increase in trade show and advertising costs and a $1.0 million increase attributed to office related expenses to support the sales team.
Question:
What was the increase in the Sales and marketing expense in 2019?
Answer: $18.1 million