Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Year | Conventional plans | HMOs | PPOs | POS plans |
| --- | --- | --- | --- | --- |
| 1998.0 | 14% | 27% | 35% | 24% |
| 1999.0 | 10% | 28% | 39% | 24% |
| 2000.0 | 8% | 29% | 42% | 21% |
| 2001.0 | 7% | 24% | 46% | 23% |
| 2002.0 | 4% | 27% | 52% | 18% |
| 2003.0 | 5% | 24% | 54% | 17% |
| 2004.0 | 5% | 25% | 55% | 15% |
| 2005.0 | 3% | 21% | 61% | 15% |
| 2006.0 | 3% | 20% | 60% | 13% |
| 2007.0 | 3% | 21% | 57% | 15% |
| 2008.0 | 2% | 20% | 58% | 12% |
Question:
How many years have HMOs been 27% and POS plans 18%?
Answer:
1.0