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:
| Name | Nationality | Club | From | Until |
| --- | --- | --- | --- | --- |
| José Manuel Abundis | Mexico | Atlanta Silverbacks | 2011 | 2011 |
| Alex Pineda Chacón | Honduras | Atlanta Silverbacks | 2011 | 2012 |
| Eric Wynalda | United States | Atlanta Silverbacks | 2012 | 2012 |
| Brian Haynes (footballer) | Trinidad and Tobago | Atlanta Silverbacks | 2012 | 2013 |
| Eric Wynalda | United States | Atlanta Silverbacks | 2014 | Present |
| Martin Rennie | Scotland | Carolina RailHawks | 2009 | 2011 |
| Colin Clarke | England | Carolina RailHawks | 2011 | Present |
| Dwight Lodeweges | Netherlands | FC Edmonton | 2010 | 2010 |
| Harry Sinkgraven | Netherlands | FC Edmonton | 2010 | 2012 |
| Colin Miller | Canada | FC Edmonton | 2012 | Present |
| Daryl Shore | United States | Fort Lauderdale Strikers | 2010 | 2013 |
| Günter Kronsteiner | Austria | Fort Lauderdale Strikers | 2013 | Present |
| Juergen Sommer | United States | Indy Eleven | 2013 | Present |
| Manny Lagos | United States | Minnesota United FC | 2010 | Present |
| Marc Dos Santos | Canada | Montreal Impact | 2009 | 2011 |
| Nick De Santis | Canada | Montreal Impact | 2011 | 2011 |
| Giovanni Savarese | Venezuela | New York Cosmos | 2012 | Present |
| Marc Dos Santos | Canada | Ottawa Fury FC | 2013 | Present |
| Colin Clarke | England | Puerto Rico Islanders | 2007 | 2011 |
| Adrian Whitbread | England | Puerto Rico Islanders | 2011 | 2012 |
| Tim Hankinson | United States | San Antonio Scorpions | 2012 | 2013 |
| Alen Marcina | Canada | San Antonio Scorpions | 2013 | Present |
| Ricky Hill | England | Tampa Bay Rowdies | 2011 | Present |
Question:
how long did colin clarke coach the puerto rico islanders?
Answer:
4 years