Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Grete Waitz
Table title:
Achievements
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Year </th><th colspan=1 rowspan=1 > Competition </th><th colspan=1 rowspan=1 > Venue </th><th colspan=1 rowspan=1 > Position </th><th colspan=1 rowspan=1 > Event </th><th colspan=1 rowspan=1 > Notes </th></tr>
<tr> <th colspan=7 rowspan=1 > Representing Norway </th></tr>
<tr> <td colspan=1 rowspan=1 > 1972 </td><td colspan=1 rowspan=1 > Olympic Games </td><td colspan=1 rowspan=1 > Munich, Germany </td><td colspan=1 rowspan=1 > heats </td><td colspan=1 rowspan=1 > 1500 m </td><td colspan=1 rowspan=1 > 4.16.0 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1974 </td><td colspan=1 rowspan=1 > European Championships </td><td colspan=1 rowspan=1 > Rome, Italy </td><td colspan=1 rowspan=1 > 3rd </td><td colspan=1 rowspan=1 > 1500 m </td><td colspan=1 rowspan=1 > 4.05.2 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1976 </td><td colspan=1 rowspan=1 > Olympic Games </td><td colspan=1 rowspan=1 > Montreal, Canada </td><td colspan=1 rowspan=1 > semi-final </td><td colspan=1 rowspan=1 > 1500 m </td><td colspan=1 rowspan=1 > 4.04.80 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1977 </td><td colspan=1 rowspan=1 > IAAF World Cup </td><td colspan=1 rowspan=1 > Düsseldorf, Germany </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 3000 metres </td><td colspan=1 rowspan=1 > 8:43.50 </td></tr>
<tr> <td colspan=1 rowspan=3 > 1978 </td><td colspan=1 rowspan=1 > World Cross Country Championships </td><td colspan=1 rowspan=1 > Glasgow, United Kingdom </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > European Championships </td><td colspan=1 rowspan=1 > Prague, Czech Republic </td><td colspan=1 rowspan=1 > 3rd </td><td colspan=1 rowspan=1 > 3000 metres </td><td colspan=1 rowspan=1 > 8:34.33 </td></tr>
<tr> <td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:32:30 </td></tr>
<tr> <td colspan=1 rowspan=3 > 1979 </td><td colspan=1 rowspan=1 > World Cross Country Championships </td><td colspan=1 rowspan=1 > Limerick, Ireland </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > IAAF World Cup </td><td colspan=1 rowspan=1 > Montreal, Canada </td><td colspan=1 rowspan=1 > 2nd </td><td colspan=1 rowspan=1 > 3000 metres </td><td colspan=1 rowspan=1 > 8:38.59 </td></tr>
<tr> <td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:27:33 </td></tr>
<tr> <td colspan=1 rowspan=2 > 1980 </td><td colspan=1 rowspan=1 > World Cross Country Championships </td><td colspan=1 rowspan=1 > Paris, France </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:25:41 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1981 </td><td colspan=1 rowspan=1 > World Cross Country Championships </td><td colspan=1 rowspan=1 > Madrid, Spain </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=2 > 1982 </td><td colspan=1 rowspan=1 > World Cross Country Championships </td><td colspan=1 rowspan=1 > Rome, Italy </td><td colspan=1 rowspan=1 > 3rd </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:27:14 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=4 > 1983 </td><td colspan=1 rowspan=1 > World Cross Country Championships </td><td colspan=1 rowspan=1 > Gateshead, United Kingdom </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > London Marathon </td><td colspan=1 rowspan=1 > London, United Kingdom </td><td class="highlighted"  colspan=1 rowspan=1 > 1st </td><td class="highlighted"  colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:25:29 </td></tr>
<tr> <td colspan=1 rowspan=1 > World Championships </td><td colspan=1 rowspan=1 > Helsinki, Finland </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:28:08 </td></tr>
<tr> <td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:27:00 </td></tr>
<tr> <td colspan=1 rowspan=3 > 1984 </td><td colspan=1 rowspan=1 > World Cross Country Championships </td><td colspan=1 rowspan=1 > New York, United States </td><td colspan=1 rowspan=1 > 3rd </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Olympic Games </td><td colspan=1 rowspan=1 > Los Angeles, USA </td><td colspan=1 rowspan=1 > 2nd </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:26:18 </td></tr>
<tr> <td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:29:30 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1985 </td><td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:28:34 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=2 > 1986 </td><td class="highlighted"  colspan=1 rowspan=1 > London Marathon </td><td colspan=1 rowspan=1 > London, United Kingdom </td><td class="highlighted"  colspan=1 rowspan=1 > 1st </td><td class="highlighted"  colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:24:54 </td></tr>
<tr> <td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:28:06 </td></tr>
<tr> <td colspan=1 rowspan=3 > 1988 </td><td colspan=1 rowspan=1 > Stockholm Marathon </td><td colspan=1 rowspan=1 > Stockholm, Sweden </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:28:24 </td></tr>
<tr> <td colspan=1 rowspan=1 > Olympic Games </td><td colspan=1 rowspan=1 > Seoul, South Korea </td><td colspan=1 rowspan=1 > – </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > DNF </td></tr>
<tr> <td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York City, USA </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:28:07 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1990 </td><td colspan=1 rowspan=1 > New York City Marathon </td><td colspan=1 rowspan=1 > New York, United States </td><td colspan=1 rowspan=1 > 4th </td><td colspan=1 rowspan=1 > Marathon </td><td colspan=1 rowspan=1 > 2:34:34 </td></tr>
</table>
Question:
In what years did Grete Waitz win the London Marathon?
Answer:
Grete Waitz marathon victories included winning the London Marathon in 1983 and 1986.