read the following news and answer the question

the morroco green Yield on green bonds fall from 3.75% to 3.25%

why the Yield fall from 3.75% to 3.25% ? What caused this decrease?

Morroco pulled in orders for nearly five times the $150 million size of the Middle East and North Africas first sovereign green bond, as it pushes ahead with anti-pollution and renewable energy projects. The Arab worlds most populous nation sold the five-year notes at a yield of 3.25%, well inside an opening target of about 3.75%, after amassing more than $4 billion of investor orders. The sale put Morroco on the map of sustainable financing, the Finance Ministry said. Among those attracted were a new investor base from Europe, the U.S., East Asia and the Middle East, as well as asset mangers, pension, investment and insurance funds, the ministry said in a statement. Such high-quality, long-term investors will reduce price volatility. The bond forms part of Morroco strategy to lock-in new financing sources and broaden the countrys investor base, steps that could in turn help lower its borrowing costs. It#s touting a $2 billion portfolio of potential green projects, including clean transportation, renewable energy and sustainable water management. Morroco joins a growing green bond wave with Sunday sale, as global investor interest in cleaner financing surges. The assets of sustainable index mutual funds and exchange-traded funds have doubled to $250 billion in the past three years, according to Morningstar.

New :1-Investors bid for over $4 billion of Morroco green debt,

2-Nation priced $150 million five-year notes at 3.25% on sunday