[number] + [counter] + 強
強, read きょう, goes straight after a number and its counter and means "just over": さんねん3年きょう強 is a little more than three years. It belongs to news, reports and business writing.
The excess is small. If the real figure is well above the number, 強 is the wrong word.
The opposite is 弱, read じゃく: "just under".
In speech, "a bit over" is usually ちょっと after the number: いち1じかん時間ちょっと. いじょう以上 is not the same: it means "or more", with no upper limit.