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:
Plitvice Lakes National Park
Table title:
Routes and distances
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Lake </th><th colspan=1 rowspan=1 > altitude (m) </th><th colspan=1 rowspan=1 > area (ha) </th><th colspan=1 rowspan=1 > depth (m) </th><th colspan=1 rowspan=1 > Group </th></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Prošćansko jezero </td><td class="highlighted"  colspan=1 rowspan=1 > 636 </td><td colspan=1 rowspan=1 > 69.0 </td><td colspan=1 rowspan=1 > 37 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Ciginovac </td><td colspan=1 rowspan=1 > 625 </td><td colspan=1 rowspan=1 > 7.5 </td><td colspan=1 rowspan=1 > 11 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Okrugljak </td><td colspan=1 rowspan=1 > 613 </td><td colspan=1 rowspan=1 > 4.1 </td><td colspan=1 rowspan=1 > 15 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Batinovac </td><td colspan=1 rowspan=1 > 610 </td><td colspan=1 rowspan=1 > 1.5 </td><td colspan=1 rowspan=1 > 6 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Veliko jezero </td><td colspan=1 rowspan=1 > 607 </td><td colspan=1 rowspan=1 > 1.5 </td><td colspan=1 rowspan=1 > 8 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Malo jezero </td><td colspan=1 rowspan=1 > 605 </td><td colspan=1 rowspan=1 > 2.0 </td><td colspan=1 rowspan=1 > 10 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Vir </td><td colspan=1 rowspan=1 > 599 </td><td colspan=1 rowspan=1 > 0.6 </td><td colspan=1 rowspan=1 > 5 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Galovac </td><td colspan=1 rowspan=1 > 585 </td><td colspan=1 rowspan=1 > 12.5 </td><td colspan=1 rowspan=1 > 25 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Milinovo jezero </td><td colspan=1 rowspan=1 > 576 </td><td colspan=1 rowspan=1 > 1.0 </td><td colspan=1 rowspan=1 > 1 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Gradinsko jezero </td><td colspan=1 rowspan=1 > 553 </td><td colspan=1 rowspan=1 > 8.1 </td><td colspan=1 rowspan=1 > 10 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Buk </td><td colspan=1 rowspan=1 > 545 </td><td colspan=1 rowspan=1 > 0.1 </td><td colspan=1 rowspan=1 > 2 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Kozjak </td><td colspan=1 rowspan=1 > 535 </td><td colspan=1 rowspan=1 > 81.5 </td><td colspan=1 rowspan=1 > 47 </td><td class="highlighted"  colspan=1 rowspan=1 > Upper Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Milanovac </td><td colspan=1 rowspan=1 > 523 </td><td colspan=1 rowspan=1 > 3.2 </td><td colspan=1 rowspan=1 > 19 </td><td class="highlighted"  colspan=1 rowspan=1 > Lower Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Gavanovac </td><td colspan=1 rowspan=1 > 519 </td><td colspan=1 rowspan=1 > 1.0 </td><td colspan=1 rowspan=1 > 10 </td><td class="highlighted"  colspan=1 rowspan=1 > Lower Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Kaluđerovac </td><td colspan=1 rowspan=1 > 505 </td><td colspan=1 rowspan=1 > 2.1 </td><td colspan=1 rowspan=1 > 13 </td><td class="highlighted"  colspan=1 rowspan=1 > Lower Lakes </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Novakovića brod </td><td class="highlighted"  colspan=1 rowspan=1 > 503 </td><td colspan=1 rowspan=1 > 0.4 </td><td colspan=1 rowspan=1 > 5 </td><td class="highlighted"  colspan=1 rowspan=1 > Lower Lakes </td></tr>
<tr> <td colspan=1 rowspan=1 > Plitvice Lakes </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > 217.0 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
</table>
Question:
How many Plitvice Lakes are there and what is the range of altitudes?
Answer:
The 16 Plitvice Lakes are separated into an upper and lower group formed between the mountains, descending from an altitude of 636 to 503 m.