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:
Loona (group)
Table title:
Singles
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=2 > Title </th><th colspan=1 rowspan=2 > Year </th><th colspan=2 rowspan=1 > Peak chart positions </th><th colspan=1 rowspan=2 > Sales </th><th colspan=1 rowspan=2 > Album </th></tr>
<tr> <th colspan=1 rowspan=1 > KOR </th><th colspan=1 rowspan=1 > US World </th></tr>
<tr> <th colspan=1 rowspan=1 > "Favorite" </th><td class="highlighted"  colspan=1 rowspan=2 > 2018 </td><td colspan=1 rowspan=1 > — </td><td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=2 > N/A </td><td class="highlighted"  colspan=1 rowspan=2 > [+ +] </td></tr>
<tr> <th class="highlighted"  colspan=1 rowspan=1 > "Hi High" </th><td colspan=1 rowspan=1 > — </td><td colspan=1 rowspan=1 > 11 </td></tr>
<tr> <th class="highlighted"  colspan=1 rowspan=1 > "Butterfly" </th><td class="highlighted"  colspan=1 rowspan=1 > 2019 </td><td colspan=1 rowspan=1 > — </td><td colspan=1 rowspan=1 > 6 </td><td colspan=1 rowspan=1 > US: 1,000 </td><td class="highlighted"  colspan=1 rowspan=1 > [× ×] </td></tr>
<tr> <td colspan=6 rowspan=1 > "—" denotes releases that did not chart. </td></tr>
</table>
Question:
When and under which Loona albums were the singles "Hi High" and "Butterfly" released, respectively?
Answer:
[+ +] was released in 2018 alongside the second single, "Hi High" and [X X] in 2019 with single, "Butterfly".