Short answer: That's the best your card can do when communicating with your AP.
Lenovo says your Y470 contains an "Intel 1000 BGN Wireless" card. Apparently it's more properly known as an "Intel WiFi Link 1000 BGN" card.
According to the Wi-Fi Alliance's certificate for that card, it is only capable of a single transmit stream (that is, it's not actually MIMO on transmit), and it is not capable of HT40 (a.k.a. "wide", 40MHz channels). In effect, it's pretty much "N in name only". The best speed it can transmit at it 65 or maybe 72.2 megabits per second.
Your card looks like it's capable of receiving 2 spatial streams at HT20, which means that with 2- and 3-spatial stream N APs (Wi-Fi routers) it could receive at up to 144.4 mbps, but unfortunately your AP is another form of non-MIMO -- and thus basically "N in name only" -- AP. It only supports a single spatial stream, although it does support 40MHz channels. So the best signaling scheme your AP and client both support is single stream HT20, which tops out at 65 mbps with a long guard interval, or 72.2 mbps with a short guard interval.
The Wikipedia article on 802.11n has a nice table of 802.11n data rates based on the number of spatial streams, 20- or 40MHz wide channels, and long or short guard intervals.
It's sad to me that so many "N in name only" products are being sold that don't really support the flavors of N that make it shine. The 65mbps that your card/AP combination tops out at isn't that much better than the 54mbps that 802.11a delivered a decade ago.