Calculate percentage average of links that contain a specific text on google sheets?

Jumping straight to the point. How can I calculate the average percentages in the screenshot below? I've tried a number of different formulas such as: sumif/countif, average(if), averageif, averageifs, arrayformula(average....)

But I get, Error, #Div/0, #value or wrong results. I would appreciate your help. I'm using the latest google spreadsheets available. See below the table.

Link

Or see below:

Page Bounce Rate

intl-en-gb 51.77%

intl-en-gb-product 21.77%

intl-en-gb-gallery 29%

intl-fr-fr-product 87%

intl-en-gb-product 42%

intl-en-gb -%

intl-de-de-product 5%

intl-fr-fr 93%

intl-en-gb-gallery 0%

What's the average Bounce Rate of all the pages that contain "intl-en-gb"?

Bounce Rate=?

What's the average Bounce Rate of the pages that exactly match "intl-en-gb"?

Bounce Rate=?

Thanks in advance!