"has been increasing slightly" is a grammatically correct phrase and can be used in written English.
It is typically used to describe a gradual or ongoing change in something. Example: "The price of gas has been increasing slightly over the past few months."
The older mothers' study highlights a phenomenon that has been increasing slightly.
Over the last 10 15 years, the annual age adjusted incidence rate for male breast cancer in the United States has been increasing slightly according to data from CDC WONDER [ 5].
Among Central American and Caribbean countries, Costa Rica's output increased by 5percentt in 2005 and may reach record levels in 2006, while in Mexico production has been increasing slightly over the past years as a result of programmes to improve genetics and herd management practices.
However, during the last decade, cases have been increasing slightly.
Now, the sales team offers tours by appointment only, and prices have been increased slightly to $197,000 for studios, $310,500 for one-bedrooms, $447,900 for two-bedrooms with two baths and $530,000 for three-bedrooms.
The battery has been increased ever so slightly, as well, in part to compensate for the newer, larger size.
Some Administration officials say the chances for a diplomatic solution have been increasing, however slightly, as the prospect of military action comes closer.
In England [ 22] and in Scotland [ 38], incidence rates for adenocarcinoma of the lung in men have been increasing only slightly and squamous cell carcinoma remains the predominant form of lung cancer in men.
Yandex's search share in Russia has only been increasing slightly in recent times so it's been getting more enterprising about how it extends its business, and moves into other products.
On fish farms which have already been privatised production is increasing slightly due to the introduction of better quality feed, better equipment for aeration and oxygenation, better regulation of the farm, as well as better management.
Other polls show that Americans' confidence in Mueller has been steady or increasing slightly in the past couple of months, though the overall level of support for his probe has varied across polls asking different specific questions.
