JPM runs a neat global bond curve index that is worth a mention:
In particular, the yield spread between the 7-10 year minus the 1-3 year maturity buckets of our global government bond index (JPM GBI Broad bond index) shifted to negative territory this week for the first time since 2007. This can be seen in Figure 2.
This is because in terms of the relative stocks of government bonds globally, there are a lot more short-dated US government bonds relative to longer-dated ones as the US has lagged other countries in terms of the duration expansion trend that took place over the past ten years.