Table:
|  |  | Years Ended December 31, |  |
| --- | --- | --- | --- |
| Process Technologies | 2017 | 2018 | 2019 |
|  | % | % | % |
| 14 nanometers and under | 0.9 | 2.6 | 0.0 |
| 28 nanometers | 16.2 | 12.6 | 11.3 |
| 40 nanometers | 28.4 | 25.3 | 23.1 |
| 65 nanometers | 12.3 | 12.5 | 14.7 |
| 90 nanometers | 4.9 | 8.3 | 13.6 |
| 0.11/0.13 micron | 11.5 | 11.6 | 12.6 |
| 0.15/0.18 micron | 12.4 | 13.7 | 13.1 |
| 0.25/0.35 micron | 10.0 | 10.1 | 8.7 |
| 0.50 micron or higher | 3.4 | 3.3 | 2.9 |
| Total | 100.0 | 100.0 | 100.0 |
Paragraphs:
Change in Product Mix and Technology Migration
Because the price of wafers processed with different technologies varies significantly, the mix of wafers that we produce is among the primary factors that affect our revenues and profitability. The value of a wafer is determined principally by the complexity and performance of the processing technology used to produce the wafer, as well as by the yield and defect density. Production of devices with higher levels of functionality and performance, with better yields and lower defect density as well as with greater system-level integration requires better manufacturing expertise and generally commands higher wafer prices. The increase in price generally has more than offset associated increases in production cost once an appropriate economy of scale is reached.
Prices for wafers of a given level of technology generally decline over the processing technology life cycle. As a result, we have continuously been migrating to increasingly sophisticated technologies to maintain the same level of profitability. We began our volume production with 65-nanometer and 40-nanometer technologies in 2006 and 2009, respectively. We introduced our 28-nanometer technology to customers in 2011 and started large-scale commercial production in 2014. Our 28nm and below technologies contributed approximately 17.1%, 15.2% and 11.3% of our foundry revenue in 2017, 2018 and 2019 respectively.
Question:
What is the increase / (decrease) in 28 nanometers from 2018 to 2019?