Switch from old 1.6 module version to 2.0 module version

1. Download new version 7.x-2.0
2. Replace old module version with new module version
3. Turn on nodeviewcount module
4. Execute following php script just once:

$node_view_count_db_select = db_select('node_view_count', 'n_v_c');
$node_view_count_db_select->fields('n_v_c', array('nid', 'uid', 'timestamp'));
$result = $node_view_count_db_select->execute()-> fetchAll();
$nodeviewcount_db_insert = db_insert('nodeviewcount')->fields(array('nid', 'uid', 'timestamp'));
foreach ($result as $item) {
  $record = (array) $item;
  $nodeviewcount_db_insert->values($record);
}
$nodeviewcount_db_insert->execute();
db_drop_table('node_view_count');

All these actions are required to save your statistics from old 1.6 module version.